As previously mentioned, chain scission reactions are dominant in PP. This is evident in the Cole–Cole plots for PP (Fig. 3)
as the arc radiuses are reduced during the processes. The changing of normalized zero shear viscosity (calculated by extrapolation
to the x-axis; g0 at g00 ¼ 0) of PP without UV as well as under different UV intensity (both mercury lamp and UV LED)
are presented at Fig. 4.